The wax moth and its control

Historic, archived document

Do not assume content reflects current
scientific knowledge, policies, or practices.

CIRCULAR No. 386 APRIL 1936

UNITED STATES DEPARTMENT OF AGRICULTURE
WASHINGTON, D. C.

THE WAX MOTH AND ITS CONTROL

By WARREN WHITCOMB, Jr., associate apiculturist, Division of Bee Culture,
Bureau of Entomology and Plant Quarantine

CONTENTS
; Page Page
Economic importance and sources of loss-___-__- 1 | Other moths causing damage to stored combs... 8
Estonyaandedistribution iss ess nea aie Sul Natural controlics. ses ae see ce a aene ee a= 8
Tifemhistony see oe eee eee AR WAT titi clalkcomtroleeee: Staessen 9
MN GYS) Ce Ae se oe OE ee 4 |. Control measures under apiary conditions. 9
SON a Vas ee te ee Se a A a 4 Control measures in stored equipment____. 9
PANY OVE) 4 ODT OYE ees oe eat I Sse em ect ee 6 Control measures in stored comb honey... 1
DOVE WEKo kU Ree es Sa ee ae ea 7

The wax moth (Galleria mellonella L.) is known under many
names in different sections of the United States. Beekeepers know
the insect as the “ wax moth”, “bee moth”, “bee miller”, “ wax
worm ”, “ web worm ”, and “ wax miller.” It is better known in the
larval or worm stage than as the adult or moth and is therefore
generally referred to as the “wax worm” or “ web worm.”

ECONOMIC IMPORTANCE AND SOURCES OF LOSS

No careful estimate has ever been made of the damage: caused by
the wax moth. The losses in Texas were at one time estimated at
5 percent, and in 1911 reports from 186 Texas beekeepers placed
colony losses at from 5 to 95 percent, according to Texas Agricul-
tural Experiment Station Bulletin 231. Losses in the Southern
States are considerably higher than in the North because of the
longer season of bee and moth activity. Moreover, apiary practices
in the South, especially that of keeping empty combs on the colonies
during long, slow honey flows, increase the opportunity for wax moth
damage. The complete destruction of colonies, however, does not
represent the total of wax moth damage, since combs in supers may
be ruined even when the colony is of fair strength. This 1s partic-
ularly true when two or more hive bodies are placed on the colonies
during slow flows, or late in the fall for storage.

Probably the most noticeable loss from wax moth injury is in
combs in storage, especially if these combs are in a warm, pro-
tected place, and consists in the destruction of the combs by the
larvae, which leave them a mass of webs and debris (fig. 1). In
the North such losses are more common than the destruction of
entire colonies.

36749°— 36——1

2 CIRCULAR 386, U. S. DEPARTMENT OF AGRICULTURE

The larvae of the wax moth cause a considerable amount of dam-
age each year to comb honey. The eggs of the wax moth are prob-
ably laid on the comb or section boxes before the comb-honey supers
are removed from the hives, but the damage usually occurs some
time after the honey has been placed in storage. The damage con-
sists of small, rather inconspicuous tunnels and borings through the
thin wax cap of the honey cells. These small holes through the
cappings cause the honey to leak out, which makes the affected sec-
tion unmarketable. This type of damage is sometimes termed
‘“ weeping.” )

A rather indirect loss that might be charged to the wax moth is
the winter loss of colonies in the Southern States. Owing to the
necessity of preventing wax moth damage to stored combs after

FIGURE 1.—Webs and tunnels made by larvae of the wax moth in a comb.

extracting, and the expense of storage room and treatment for such
combs, many beekeepers store supers of these empty combs on the
colonies during the winter. This gives added room for the bees to
occupy during a warm spell, and a sudden change in temperature
may chill or even kill. them before they can return to the cluster. It
also gives an opportunity for the dissipation of colony heat and
thereby increases the quantity of food consumed by the bees, and,
during long periods of cold or inclement weather, weak colonies or
colonies short of stores may starve. In many such cases of starva-
tion the wax moth destroys the combs before the beekeeper becomes
aware of the death of the colony.

THE WAX MOTH AND ITS CONTROL 3

In any study of the economic importance of an insect, not only
the loss but the benefit from the insect must be weighed. The wax
moth is not an unmitigated evil. In the first place, the destruction
of combs by the wax moth has not only tended to prevent the keep-
ing of bees in box hives but has also tended to improve general bee-
keeping practices. The wax moth has also been an ally of the bee-
keeper by helping to destroy combs in bee trees or other inaccessible
places, which might harbor germs of some of the brood diseases.

Since bees in box hives cannot be examined, requeened, or other-
wise controlled, the colonies are likely to become weak, and under
such conditions an invasion of the wax moth destroys the colony
and the combs. Many States have laws to prevent the keeping of
bees in box hives, and the wax moth has furthered the aim of this
legislation by destroying such colonies in its spread. So thorough
is the destruction of colony and combs in most box hives that, unless
there are large stores of honey in the hives, bees are no longer
attracted to them.

Particularly in the Southern States, where the honey flow is slow
and extends over a long period, it has become a practice to give more
super room at the beginning of the flow than the bees actually need.
This is not the best practice if a large crop of honey is desired, and
the destruction of such unprotected combs by the wax moth has been
of direct benefit to beekeepers in forcing a change of method.

The destruction by wax moth larvae of combs in bee trees is prob-
ably a great aid in preventing the spread of bee disease through the
robbing of honey by other bees and, in those areas where queen
breeders and package shippers are located, the destruction of stray
colonies has also been of real value. Since the germs of American
foulbrood have been found in the excrement of wax moth larvae
there is a theoretical possibility that the disease might be spread
by this means, but actually there is no evidence to warrant pinning
additional guilt on this pest.

The benefits of the wax moth are small, however, when compared
with the losses of entire colonies and of stored combs, or the extra
care and manipulation necessary to combat the insect.

HISTORY AND DISTRIBUTION

The earliest works on beekeeping contain references to the wax
moth. Aristotle (884-822 B. C.), Virgil (70-19 B. C.), and Colu-
mella (middle of the first century, A. D.), all mention the wax moth
as an enemy of the honeybee. |

The range of foods that can be eaten by the larvae of the wax
moth would suggest that it might at one time have had other foods
than those obtainable in the hive, but at present wax comb in some
form is practically its only food.

F. B. Paddock, who has made a study of the present-day distribu-
tion of the wax moth, was unable to determine the date of its intro-
duction into the United States. From his distribution records some
interesting inferences may be drawn: (1) The wax moth has been
spread by man more than by the natural activity of the moth. The
introduction of the moth into Sweden with beehives from Germany
prior to 1750 and its introduction into Australia, New Zealand, and
other island regions all point to the conclusion that the wax moth

4 CIRCULAR 386, U. S. DEPARTMENT OF AGRICULTURE

must have been aided in its distribution by man and by poor bee-
keeping methods. (2) The insect finds its most favorable conditions
in the Temperate Zone. According to Paddock, the wax moth is
present in Ontario, Canada, but has been unable to establish itself
in Manitoba and British Columbia. The high altitudes of the Rocky
Mountains are also free, but the wax moth can be found almost any-
where else in the United States where there are bees.

In the Southern States the wax moth does damage practically
throughout the year, with the possible exception of December, Jan-
uary, and February; and during mild winters wax moths may ap-
pear even in January. It is probable that colonies are infested, at
least with eggs, throughout the whole season of bee activity and that
only in active colonies is wholesale damage prevented. In supers
and hive bodies brought from the apiary and stored, larvae of all
stages will be found, ordinarily within a week, unless the combs are
treated. Under storage conditions, the lengths of the egg, larval, and
pupal stages vary considerably, and the number of broods per year
is largely determined by temperature and humidity. Distribution,
under such conditions, is rapid because of the movement of combs
and bee equipment, even without the active flight and dispersion of
the adult moths.

LIFE HISTORY

THE EGG

The egg of the wax moth is small, white, somewhat elliptical, and
rather inconspicuous (fig. 2). It measures about one fifty-fourth of
an inch in greatest length and about one-sixtieth of an inch in great-
est width. The size and shape vary somewhat, depending on the
number of eggs laid in one spot and the character of the site in which
they are laid.

At 75° to 80° F. the eggs hatch in from 5 to 8 days, but with low
temperatures (50° to 60°) the period may extend to 35 days. Under
aplary conditions the incubation period is probably almost entirely
dependent on temperature.

The eggs of the wax moth are probably laid most frequently in
the cracks between hive parts; that is, between supers, between hive
body and bottom board, or between the super and cover. Egg masses
have been found in cracks between the inner cover and top super of
the hive, where they had been deposited by the female, apparently
from the outside of the hive. Eggs are also laid inside the hive in
more or less unprotected places. Under controlled conditions, when
females were allowed access to combs, the eggs were found on the
comb (fig. 2) along the edges of the frames and almost always in
the portions of the hive farthest from the light. Egg masses in the
hive are difficult to see and may often be overlooked.

THE LARVA

The young larvae, upon hatching, are very active and do not look
like the familiar wax worms. Beekeepers have called them wood lice
and have not connected the appearance of these forms with the dam-
age from the worms, which they noticed later. They are often seen
upon the inner covers of hives and in the cracks between supers and

THE WAX MOTH AND ITS CONTROL 5

hive parts. They are less often observed within the hive, especially
those with strong colonies, partly because they are very small and
very active, and partly because they resemble the wax in color.

The young larvae attempt to burrow into the wax almost imme-
diately after emergence from the egg. The first burrows are often
incomplete and may be mere roughenings of the surface of the wax.
After the first day, however, they make small tunnels between the
cells and toward the midrib of the comb, in which the typical silken
strands of the web may be found.

The growth of the larvae depends upon several factors, of which
the quantity and quality of food and the temperature are most

FIGURE 2.—Eeggs of the wax moth laid on a comb. Greatly enlarged.

important. The length of the larval period, from the time of the
hatching of the egg until pupation, has been found to range from
28 days to 4 months or even as long as 140 days or nearly 5 months.
During this period the large larvae have grown from about one
twenty-fifth of an inch to seven-eighths of an inch in length.

The food of the larvae is not confined to beeswax, and it is even
probable that little pure wax is digested but rather that the larvae
derive most of their nourishment from the impurities in the wax.
Foundation, especially in frames, is seldom attacked and then usually
only by the small larvae. In some cases newly emerged larvae have
been seen chewing, or attempting to chew, other larvae which had
been injured. .

The larvae prefer the darker brood combs to the white extracting
combs. In the brood combs the larvae confine their work mostly
to the midrib and bases of the cells, and combs are often found with
perhaps the outer one-fourth of the length of the cells untouched
and the central portion, including the midrib, completely destroyed
and replaced with a mass of web and refuse. Under such conditions

6 CIRCULAR 386, U. S. DEPARTMENT OF AGRICULTURE

the cells containing pollen are mostly avoided, although cells con-
taining honey may be riddled. It is known, however, that larvae
will eat pollen and develop on it. Wax moth larvae sometimes chew
off the cappings of the cells containing sealed brood, and, while the
bees may repair some of the damage, many cells will be left only
partially closed.

Although larvae can develop on foundation, the mortality of such
larvae is high, and the developmental period of those which survive
is much longer than that of normally fed larvae, and the resulting
adults are small and almost white. It is almost certain that damage
reported by beekeepers in Louisiana as caused by the lesser wax
moth (Achroia grisella Fab.) is caused by such poorly fed larvae of
Galleria mellonella, since no specimens of the true lesser wax moth -
were observed during the author’s studies. When the larvae are
forced to exist on the lighter comb and the outer portions of the
cells which have been left untouched by the previous broods, the
damage done by them, such as the webbing and external feeding,
and their later appearance greatly resemble the work and appearance
of the lesser wax moth.

The optimum temperature for the development of the larvae is
between 85° and 95° F., about that normally found in a beehive
during the active season. At lower temperatures development is
slower, but, unless the temperature falls below 60°. no other influence
on the larva has been noted. At temperatures of 40° to 45° the
larvae seem to become dormant, and no feeding or growth takes
place.

THE PREPUPA

Before pupation the full-grown larvae spin a dense, tough, silken
cocoon. Usually this cocoon is firmly attached to the side of the
hive, to the frame, or other solid support, but in some cases the
cocoons are found in the mass of tunnels and refuse of the wax of
the frames or on the bottom of the hive (fig. 3). In many cases a
hollow is chewed out of the wood of the hive or frame, and the
cocoon is placed in this for added protection. Frames may be found
in which holes have been bored completely through the end or top
bars, and the cocoon and pupal case will be found inside these
holes. This habit of the wax worm is responsible for a considerable
part of the damage caused by the insect, since in heavily infested
colonies not only the wax but also the frames are destroyed. In such
cases particles of the wood borings are incorporated in the cocoon,
which is then well disguised. The fully grown larvae migrate to
considerable distances before the cocoons are spun, and pupal cases
may be found beneath the hive and even on the more protected
parts of the hive stand.

THE PUPA

Within the cocoon the larva changes to the pupa. The duration
of the pupal stage within the cocoon ranges from 8 to 62 days,
depending on temperature. As with many other insects, the pupal
period allows the wax worm to pass through the fall and winter
protected against climatic influence to a large extent. In the South,
especially during warm winters, the adults may emerge at any time
during the winter.

THE WAX MOTH AND ITS CONTROL Fi
THE ADULT

The adult wax moths are about three-fourths of an inch in length
and have a wing spread of about 1 to 114 inches in well-developed
specimens. They are commonly seen in the resting position with
thaw grayish-brown wings folded, rooflike, closely about them
(fig. 4, A and B). The moths are not easily disturbed, but when
molested they run rapidly before they take wing. The males are
slightly smaller than the females and may be distinguished from
them by the shape of the outer margin of the fore wing, which is
smooth in the female but roundly notched in the male. The sexes

FIGURE 3.—Pupal cases, or cocoons, of the wax moth.

may also be distinguished easily by the palpi of the mouth parts,
which are prominent in the female but absent in the male.

The moths vary widely in size and color, according to the type of
food consumed by the larvae and to the length of time of develop-
ment. Small, poorly nourished larvae, or those which, because of
low temperatures or other factors, develop slowly, transform into
small adults, sometimes less than half the normal size. Such small
adults might easily be confused with the lesser wax moth. Larvae
fed on dark brood combs transform into adults which may be dark
gray to almost black, while larvae which survive on pure wax, or on
foundation, transform into moths that are silvery white and smaller
than those reared on brood comb.

The female starts depositing eggs from 4 to 10 days after emergence
and continues depositing them as long as her bodily vitality lasts.
Egg laying may be rapid at times, and as many as 102 eggs have been
deposited by a female in 1 minute. The total number of eggs laid by

8 CIRCULAR 386, U. 8. DEPARTMENT OF AGRICULTURE

a female varies to a considerable extent under laboratory conditions,
but it is usually less than 3800. The adults may live as long as 3 weeks.

NUMBER OF BROODS

It seems doubtful whether there are definite generations of the wax
moth during different periods of the year in the Southern States.
Rather it is probable that the moth is always present, that larvae in
all stages, pupae, and adults may be found at any time, and that devel-
opment goes on except during periods of low temperature.

iC

Ficurre 4.—Adults of the wax moth: A and B, With wings folded; C and D, with wings
spread; A and C, females; B and D, males. Note the deep clefts in the tips of the fore
wings of the male,

OTHER MOTHS CAUSING DAMAGE TO STORED COMBS

Mention has been made of the lesser wax moth, but this moth does
not cause so much damage to stored combs as does the wax moth. ‘The
work of the lesser wax moth is similar to that of the wax moth, but
the tunnels are smaller, the webs finer, and feeding and webbing are
more confined to the outer surface of the combs. The Mediterranean
flour moth (L'phestia kuehniella Zell.) is a pollen feeder rather than
a wax feeder but does some damage to combs by boring tunnels
through the midrib. This moth also tunnels into brood cells and
consumes the food intended for the developing bee larvae. These
moths, also, may be controlled by the methods given in this circular.

NATURAL CONTROL

The bees are the greatest and most effective natural enemies of the
wax moths. They will, when the colony is strong, carry them bodily
out of the hive, and there is no better insurance against the ravages
of the pest than to have the combs populated with a strong colony
headed by a vigorous queen.

A small red ant (A/onomoriwm sp.), which seems to have a wide
range of foods, has been quite effective in controlling the wax moth
in laboratory experiments by feeding on resting wax moths during
daylight, but it has not been observed attacking larvae in combs under

THE WAX MOTH AND ITS CONTROL 8)

apiary conditions. The ant seems more attracted to honey and pollen
than to the wax moth in stored combs.

Comparatively little is known of the other insect enemies of the
wax moth, and not much benefit can be expected from them.

Climatic conditions, particularly temperature, are effective in limit-
ing the spread of the wax moth, and the rate of growth, and thereby
the amount of damage done by the insect.

ARTIFICIAL CONTROL

CONTROL MEASURES UNDER APIARY CONDITIONS

Two phases of artificial control for the wax moth must be dis-
cussed, (1) the control measures for colonies under apiary conditions,
and (2) control of the wax moth, or prevention of its damage, in
stored equipment.

Under apiary conditions, the best control is in keeping colonies
strong. Added to this should be cleanliness of hives—removal of
propolis, bur combs, and refuse on the bottom board which provide
protection for larvae of the wax moth. Even in strong colonies,
developing larvae of the wax moth may often be found beneath the
comb burs on the bottom board or in propolis and bur combs in the
less accessible portions of the hives. Accidental loss of queens in
such colonies late in the fall may mean the loss of colonies from wax
moth damage before the first spring examination. . Beekeeping prac-
tices and manipulations should be based on the assumption that. the
wax moth in some stage may be present in the hives at all times.

The box hive, or a hive in which the frames are not easily movable,
gives the wax moth an opportunity to reproduce, and forms a breed-
ing place from which other colonies may be attacked. From the
standpoint of both productive beekeeping and wax moth control, such
hives should be destroyed and replaced by modern equipment.

Control of the wax moth by trapping the adults at hghts or by
trap combs has not been successful. The adults are not attracted to
lights and trap combs evidently are not more attractive.

CONTROL MEASURES IN STORED EQUIPMENT

For controlling the wax moth on equipment in storage, two methods
of attack are possible. Some substance may be used which will kill
the wax moth or some method adopted of repelling the adults so that
eggs are not deposited on the stored equipment. Of the killing sub-
stances, fumigants (poisonous gases) have proved most satisfactory,
but, with the exception of paradichlorobenzene, the gases do not
remain in the supers long enough to have any distinct repellent action.

Fumigants for wax moth control are substances, whether liquid or
solid, that form a killing gas that diffuses through the stored equip-
ment and is taken in by the insect. Several different substances have
been used with success against the wax moth, particularly paradi-
chlorobenzene and carbon disulphide.

PARADICHLOROBENZENE

Paradichlorobenzene (“PDB”) is a white crystalline substance
which changes slowly into a gas. The gas is not unpleasant to smell,
is noninjurious to people at the concentration obtained when used as

10 CIRCULAR 386, U. 8. DEPARTMENT OF AGRICULTURE

directed, and is heavier than air. It is noninflammable and nonex-
plosive. It kills adults and larvae of the wax moth but is not
effective against the eggs.

In fumigating with paradichlorobenzene, the supers should be
stacked as tightly as possible and the cracks between supers covered
with gummed paper strips (fig. 5). A generous handful of the crys-
tals should be placed on the top of the frames of the top super and
the cover put tightly in place. The crystals may be sprinkled di-
rectly on the top bars of the frames, as in figure 5, or put on a piece

FIGURE 5.—Supers loaded with comb ready for fumigation. The joints are sealed with
gummed paper tape, and the crystals of paradichlorobenzene have been sprinkled
heavily over the top bars.

of paper laid on the top bars. Since the gas is nonpoisonous and
not disagreeable, treatment may be made in ordinary storage without
taking the infected material out of doors. At intervals during the
storage season the covers of the stacks should be raised, and unless
some are still present, more crystals added.

Paradichlorobenzene is at present as cheap as any of the materials
mentioned in this circular, with the exception of sulphur, and is by
far the easiest and least dangerous to use. The crystals last for some
time, since they volatilize slowly, and not only kill the larvae and
adults first present and the larvae as they hatch from the eggs, but
repel moths from outside which might otherwise enter and start a
fresh infestation. Paradichlorobenzene is most effective at tempera-
tures above 70° F. and volatilizes more rapidly as the temperature
rises. Inspections of stored materials should be made at intervals
of 2 or 3 weeks, depending on the temperature of the storehouse and
the prevalence of adult moths,

THE WAX MOTH AND ITS CONTROL 11

CARBON DISULPHIDE

Carbon disulphide has been a standard fumigant for wax moths
and similar insects until recently, and with proper precautions is still
satisfactory. As commonly sold commercially, it is a more or less
yellowish, somewhat oily liquid that changes readily at ordinary
temperatures into an ill-smelling gas. The hquid is about one-fourth
heavier than water, and the gas is heavier than air. Jt is highly
inflammable, and the vapor is explosive when mixed with ar in
certain proportions, and therefore this chemical must not be handled
around fire of any kind. Preferably it should be used out of doors
or in a well ventilated or open shed.

In using carbon disulphide the supers should be sealed in the
same manner as for paradichlorobenzene. One ounce of liquid is
sufficient for five supers, and more than this number of supers should
not be placed in a single stack, since the weight of the gas carries
it quickly to the bottom of the stack, and the top super may not be
adequately fumigated. The stack should remain sealed for not less
than 12 hours. Carbon disulphide is effective against larvae and
adults but not against eggs; consequently, it may be necessary to
repeat the treatment after any eggs have had time to hatch.

FUMIGANTS THAT ARE LESS EFFICIENT FOR WAX MOTH CONTROL

Other substances may be used for the control of the wax moth in
stored equipment, but, as explained in the following paragraphs,
they are not so efficient for this purpose as either paradichloro-
benzene or carbon disulphide and are therefore not recommended.

The fumes from burning sulphur effectively control the larvae and
adults of the wax moth but are ineffective against the eggs. Sulphur
was one of the earliest of the substances used to control the wax
moth in stored combs. The early method was to stack the supers
over a pan of live coals over which was sprinkled powdered sulphur.
About 2 ounces of powdered sulphur (flowers of sulphur) is suffi-
cient for a stack of five supers. At least one empty super should
be placed at the bottom of the stack so that the heat will not melt
the combs. Present-day practice is to put the sulphur in a dish,
wet it with denatured or wood alcohol, and ignite it directly. The
work should be done in a well-ventilated room or out of doors, and
precautions must be taken against ignition or overheating of the
combs.

Calcium cyanide is effective against the larvae, pupae, and adults of
the wax moth, but cannot be depended on to destroy the eggs. It
is obtainable either as dust or as fine or coarse crystals. For use
in fumigating bee equipment the crystals are preferable to the dust.
In the presence of moisture (such as that found in the air) the
crystals form a deadly gas, noninflammable and nonexplosive, but
extremely poisonous to people and animals. Care must be taken
when using the substance, and the gas must not be breathed. For
use put one full tablespoonful of crystals on a sheet of paper and
place the paper on the top of the frames in a super. Quickly place
the other supers on top, using not more than five supers per stack,
and tape the joints between supers with gummed paper tape. The
fumigation should be done out of doors, or in a well-ventilated room.

1D CIRCULAR 386, U. S. DEPARTMENT OF AGRICULTURE

Leave the stack for at least 12 hours before disturbing it, and air
the supers well before storing them.

Carbon tetrachloride is effective against wax moths, but does not
have enough penetrating power to kill larvae in cocoons or in thickly
webbed refuse. It is a colorless liquid with a sweetish, disagreeable
odor. The gas formed is heavier than that of carbon disulphide,
and it is used in the same way. ‘The gas is noninflammable and non-
explosive, but poisonous. :

GENERAL DIRECTIONS AND SUMMARIZED INFORMATION ON THE USE OF FUMIGANTS

Use not more than five supers in a stack and seal the joints with
gummed-paper tape to make the stack gas tight. With gases heavier
than air, make sure that the base of the stack is tightly closed, since
the gases sink to the bottom of the stack and may escape. A pad of
newspapers placed beneath the stack will help to confine the gas.

Fumigate out of doors, if possible, or at least in a well-ventilated
room. Read carefully the directions for using the selected fumigant
and have everything in readiness before fumigation is begun, espe-
cially if cyanide is to be used.

Caution.—Carbon disulphide gas is highly explosive, and any
chance of ignition must be carefully guarded against. Both carbon
disulphide and. calcium cyanide and their gases are poisonous to
people and to animals and must be stored and handled with extreme
care.

When using paradichlorobenzene, put the crystals directly on the
top bars of frames of the top super, as shown in figure 5, or on a
paper laid on the top bars, and renew them throughout the season
whenever the crystals have disappeared. .

As the other fumigants mentioned are not effective against rein-
festation from hatching eggs, examinations must be made at intervals
to see if any eggs have hatched, especially if the storage room is
warm. If the temperature is above 70° F., repeat the treatment after
2 or 3 weeks. The stacks being fumigated must be kept sealed for at
least 12 hours, and preferably for 24 hours.

Air the combs thoroughly before placing them on the hives.

Table 1 gives an outline for reference in fumigating against the
wax moth.

CONTROL MEASURES IN STORED COMB HONEY

The control for wax moth damage to stored comb honey is the same
as for other stored comb products. The supers should be removed
from the colonies as soon as possible after the flow ceases and piled
in tiers of not more than 8 to 10. All joints between supers should
be covered with paper, and the bottom of the stack should be sealed
to prevent leakage of gas. Paradichlorobenzene crystals should be
sprinkled over the sections of each super as it is placed in the tier, as
well as on the sections of the top super, since circulation of air is
poor in such stacks. The treatment should be continued until the
honey is graded and marketed. Carbon disulphide may be used
according to the directions given, if desired.

13

CONTROL

AND ITS

THE WAX MOTH

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ORGANIZATION OF THE UNITED STATES DEPARTMENT OF AGRICULTURE
WHEN THIS PUBLICATION WAS LAST PRINTED

Secretary of Agriculture_______ = d Henry A, WALLACE.

Under Secretary 22 ae ee ReExrForD G. TUGWELL.
Assistant Secretary______-—__ =i Bie _ M. L. WIxson.

Director of Extension Work_.~------------_ C. W. WARBURTON.

Director. of. Personnels ee W. W. STOCKBERGER.

Director of Information_-__ __-—==eee ss M. S. EISENHOWER.

DireCtor Of el inane a2 ea es See eee eee W. A. JUMP.

NSOUGIIOT 2 2e= ee ke a See eee MASTIN G. WHITE.
Agricultural Adjustment Administration_____ CHESTER C. Davis, Administrator.
Bureau of Agricultural Heonomics___________ A. G. BLAck, Chief.

Bureau of Agricultural Engineering_________- S. H. McCrory, Chief.

Bureau of Animal Industry_________________ JOHN R. MoHLER, Chief.
Bureau of Biological Survey_— oF a meas — IRA N. GABRIELSON, Chief.
Bureau of Chemistry and Soils__-__________ H. G. Knigut, Chief.

Bureau of Diiry Industy = ee O. E. ReEeEp, Chief.

Bureau of Entomology and Plant Quarantine. Lem A. Strone, Chief.

Office of Hxperiment Stations_______________ JAMES T. JARDINE, Chief.

Food and Drug Administration— _.....__ WALTER G. CAMPBELL, Chief.
Ronestaservice = zs __. FERDINAND A. Siuncox, Chief.
Grain Futures Administration_________--__-_ J. W. I. DUvEL,;. Chief.
Bureau of Home Heonomics__ — === Louise STANLEY, Chief.
LAOTONY) 2 S252 ee 2 he 5 ee eee CLARIBEL R. BARNETT, Librarian.
Bureau of Plant Industry____________-___-__ FReperick D. Ricury, Chief.
Bureau of Lubic kos Se THomas H. MacDona.p, Chief.
Sou, Conservation Service H. H. BENNETT, Chief.
Weather Buredu___--_-_-—-— ake oes WHELs Re GRecG sO iver.

This circular is a contribution from

Bureau of Entomology and Plant Quarantine__. Ler A. Strone, Chief.
Division of Bee Culture eee JAS. I. HAMBLETON, Principal Api-
culturist, in Charge.
14

U.S. GOVERNMENT PRINTING OFFICE: 1936

For sale by the Superintendent of Documents, Washington, D, C. - - - - - - Price 5 cents

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